Field of the Invention
The invention relates to an exhaust gas treatment device for generating an electric potential and/or an electric field and/or plasma. The intended effect of the plasma is to at least agglomerate or electrically charge soot particles in a flow of exhaust gas, thus promoting deposition of the particles in a particle filter. Such an exhaust gas treatment device can be employed in a motor vehicle, for example. The invention also relates to a method for treating exhaust gas and a motor vehicle having the device.
In the case of motor vehicles with mobile internal combustion engines and, in particular, in the case of motor vehicles with a diesel drive, the exhaust gas from the internal combustion engine generally contains quantities of soot particles, and they must be discharged into the environment. That is stipulated by corresponding exhaust gas regulations, which specify limits for the number and mass of soot particles per unit of exhaust gas weight or exhaust gas volume and, in some cases, also for an entire motor vehicle. Soot particles are, in particular, unburned carbon and hydrocarbon compounds in the exhaust gas.
The fact that the provision of an electric field and/or a plasma causes agglomeration of small soot particles into larger soot particles and/or causes an electric charge in soot particles, is known. Electrically charged soot particles and/or relatively large soot particles are generally very easy to remove in a filter system. Due to their relatively high inertia, soot particle agglomerates are transported more sluggishly in a flow of exhaust gas and thus settle more easily at points where a flow of exhaust gas is deflected. Due to their charge, electrically charged soot particles are attracted to surfaces, accumulating on those surfaces and losing their charge. That, too, facilitates the removal of soot particles from the stream of exhaust gas during the operation of motor vehicles.
The systems already proposed for generating and/or (temporarily) maintaining an electric field and/or plasma are generally very complex technically and/or inadequate in terms of efficiency. It has likewise been possible to identify problems with the formation of a uniform electric field and/or an electric field matched selectively to the flow of exhaust gas. At any rate, none of the existing systems appears to be ready for series production as part of motor vehicle construction.